Plus there must be some basic information already going to the lens. Otherwise, how does it know when to stop down and for how long? Maybe a feature we'll see on the Canon medium format camera? 1/1000 flash synch times would be a big selling point.

An in-lens leaf shutter in a couple of high end lenses would be very nice. At smaller apertures it should be possible to get flash sync at the fastest shutter speed the shutter allows, and at larger apertures it should still be much faster than at 1/250th of a sec - probably around 1/1000th of a sec.

However, leaf shutters do add an additional type of vignetting at faster shutter speeds - when they're operating at their absolute maximum speed, the centre of the frame is open from the start of the exposure right the way through to the end - but go to half way out on the sensor, and 1/4 of the time into the exposure the sensor finally gets light hitting it, and 3/4 of the way through, it closes again - so at that part of the sensor, there's only 50% of the light. At the extreme corners, the aperture only opens momentarily, so close to 0% of the light hits it. Therefore it would be nice if there was an option to select which of the two shutters is used if such a lens is mounted - leaf shutter for flash work, and focal plane shutter for non-flash work.

No EF lens has a shutter in it. Canon DSLR's have a focal plane shutter - that is a shutter which is just in front of the focal plane (the sensor). These work by sweeping vertically over the sensor. At a slow shutter speed, its all nice and simple - the first 'curtain' sweeps across the lens, allowing the light to hit the sensor. And after a bit of time the of shutter being open, the second 'curtain' the sweeps across the lens, closing it to light. The curtains can only cover their ground at a set speed, so the shutter speed is controlled by how long after the first curtain the second curtain is triggered. At the flash sync speed, the second curtain is triggered when the first curtain has completed its movement, which means there is just the tiniest moment when the whole sensor is exposed - that is when the flash fires. At faster speeds (typically 1/250th of a sec or faster), the second curtain has set off before the first curtain has finished, so the sensor is never entirely exposed - if a single flash was to fire then, part of the frame would be exposed without the flash. Up at the fastest shutter speed, there will usually be just a tiny slit of an opening between the two curtains, sweeping its way over the sensor. To get high speed sync to work at such shutter speeds, the flash fires at a low power multiple times to get the entire sensor exposed to flash light.

A leaf shutter is usually located inside the lens, and its life is easier as it is typically placed at the narrowest part of the light path, by the aperture. And it works in much the same way as aperture blades do - it is circular, and it starts off closed, opens up to the diameter of the aperture, and then closes again. This means that at any shutter speed there will always be a time where the shutter is fully open - hence the very fast sync speeds available with such a shutter. But the fastest shutter speed reduces at wider apertures as the shutter can't cover all that extra ground as fast, and it does lead to an increase in the vignetting as detailed in my previous post.

Having both available, and using whichever one is best for the situation (with or without flash) would give the best of both worlds.

paul13walnut5

If canon were to seek to offer the benefits associated with a leaf shutter then I think the more likely route would be to equip a camera with a fast electronic shutter - i.e. a faster electronic readoff sensor, perfectly feasible with CCD based cameras at present in high end conventional video cameras. This would also solve artefacts such as rolling shutter.

I know the CMOS technology is in some regards catching up with CCD's, but I'm very surprised the likes of Sony, who pioneered FIT ccds 15 years ago -and who are very keen on making sure Canon don't steal the industrial camcorder market- haven't jiggled some of their tech around.

We know Sony can make CCD's this size, the challenge is can they do it with a fast enough read-off, and enough megapickles for stills users and at a reasonable cost.

I would say that this kind of approach, which wouldn't require special lenses, and is camera based, at a premium for those who need it (studio photographers) would be a practical way forward. Ideally for us of course, Canon would either develop such a chip themselves, or buy it in from Sony (and why not? historical precedent, dividends for Pentax and Nikon if you DXO watch..)

An in-lens leaf shutter in a couple of high end lenses would be very nice. At smaller apertures it should be possible to get flash sync at the fastest shutter speed the shutter allows, and at larger apertures it should still be much faster than at 1/250th of a sec - probably around 1/1000th of a sec.

However, leaf shutters do add an additional type of vignetting at faster shutter speeds - when they're operating at their absolute maximum speed, the centre of the frame is open from the start of the exposure right the way through to the end - but go to half way out on the sensor, and 1/4 of the time into the exposure the sensor finally gets light hitting it, and 3/4 of the way through, it closes again - so at that part of the sensor, there's only 50% of the light. At the extreme corners, the aperture only opens momentarily, so close to 0% of the light hits it. Therefore it would be nice if there was an option to select which of the two shutters is used if such a lens is mounted - leaf shutter for flash work, and focal plane shutter for non-flash work.

I would assume that would be easy to correct in post or even in camera.

A leaf shutter needs to be located very close to the aperture. At very fast shutter speed, the limited speed of the shutter would have an impact on the effective aperture: at open aperture, you would get less blur, because the effective aperture is smaller for a fraction of the exposure time. The leaf shutter will not cause vignetting, unless it is located closer to the sensor.

Back to the initial question: No, from the marketing perspective it does not make sense. The demand is very low. Development cost is significant. Additional costs for the lenses, camera HW and SW are significant (in the manufacturer's terms). How big would be the impact on sales numbers? There is no profit to expect. That's just my opinion, of course.

I was wrong, I never used my Hasselblad lenses that way, there is a pc connector on the lens that I thought could be used to operate the shutter, but in reviewing the manual, I now realize that its for flash and does not close the shutter. you can see it in the photo.

You can adapt a leaf shutter to a DSLR, just get a Hasselblad lens and adapter. It might take a little experimenting, but you can do it with no problem, except its all manual.

I started thinking this way too. My solution was to put the camera in a mode similar to sensor cleaning that would keep the focal plane shutter open and the sensor ready for action. Aperture and shutter speed would be dialled in manually on the lens. From there, you would simply trigger the lens via an old school cable release that is attached to the lens itself. Mamiya RB67 and RZ67 lenses work this way in mirror lock up mode.

In theory, it would work perfectly....except you'd have a flat battery in half an hour. Back to the drawing board.